1. Field of the Invention
The present invention relates to a remote control toy car and, more particularly, to a three-gear position type transmission mechanism for a remote control toy car.
2. Description of the Related Art
Regular gasoline engine remote control toy cars commonly use a transmission mechanism to increase the torque. However, because the transmission mechanism of a conventional gasoline engine remote control toy car provides only one transmission mode, it is less efficient to accelerate the speed, and the torsion cannot be increased during low speed. In order to eliminate these problems, dual-gear position transmission mechanisms are developed. However, a dual-gear position transmission mechanism is still not sufficient to move a toy car upwards on a slope at a high speed.
The present invention has been accomplished to provide a three-gear position type transmission mechanism for a remote control toy car, which eliminates the aforesaid drawbacks. It is one object of the present invention to provide a three-gear position type transmission mechanism for a remote control toy car, which uses a three-gear position transmission gear set to match with an idle gear set, enabling the toy car to automatically shift the gear position under a high revolving speed when moving upwards on a slope. To achieve this an other objects of the present invention, the three-gear position type transmission mechanism comprises a tubular transmission shaft, said tubular transmission shaft having a polygonal segment in a circularly tubular shaft body thereof; a transmission gear set mounted on the tubular transmission shaft, the transmission gear set comprising a first transmission gear wheel mounted on a two-way axle bearing at the tubular transmission shaft for two-way rotary motion, the first transmission gear wheel comprising an external gear and an internal gear, a second transmission gear wheel mounted on a two-way axle bearing at the tubular transmission shaft for two-way rotary motion, the second transmission gear wheel comprising an external gear, an internal gear, and a clutch adapted for engaging the internal gear of the first transmission gear wheel for enabling the first transmission gear wheel to be rotated with the second transmission gear wheel, a third transmission gear wheel mounted on the tubular transmission shaft for one-way rotary motion with the tubular transmission shaft, the third transmission gear wheel comprising a polygonal center hole coupled to the polygonal segment of the tubular transmission shaft, an external gear, and a clutch adapted for engaging the internal gear of the second transmission gear wheel for enabling the second transmission gear wheel to be rotated with the third transmission gear wheel; a driven gear wheel fixedly fastened to the first transmission gear wheel; and an idle gear set, the gear set comprising a center shaft supported on two-way axle bearings, a first idle gear fixedly mounted on the center shaft meshed with the external gear of the first transmission gear wheel, a second idle gear mounted on a one-way axle bearing at the center shaft and meshed with the external gear of the second transmission gear wheel, and a third idle gear mounted on a one-way axle bearing at the center shaft and meshed with the external gear of the third transmission gear wheel. When the driven gear wheel rotated by an external drive unit to rotate the first transmission gear wheel, the third idle gear is driven to rotate the third transmission gear wheel and the tubular transmission shaft at a low speed. The clutch of the third transmission gear wheel is forced outwards by a centrifugal force into engagement with the internal gear of the second transmission gear wheel when the revolving speed of the third transmission gear wheel surpassed a predetermined level, thereby causing the second transmission gear wheel and the second idle gear to be synchronously rotated with the tubular transmission shaft and the third transmission gear wheel at a middle speed. The clutch of the second transmission gear wheel is forced outwards by a centrifugal force into engagement with the internal gear of the first transmission gear wheel when the revolving speed of the second transmission gear wheel surpassed a predetermined level, thereby causing the first transmission gear wheel, the second transmission gear wheel, the third transmission gear wheel, the first idle gear, the second idle gear, the third idle gear, and the tubular transmission shaft to be rotated at a high speed.